Publication Date:
2012-03-30
Description:
Tisbe furcata , Nitokra lacustris , Calanus finmarchicus and Calanus glacialis were reared for several months in the laboratory prior to feeding selected diets. Copepods were fed Isochrysis galbana , Tetraselmis sp., Dunaliella tertiolecta , Thalassiosira pseudonana , Rhodomonas sp., Rhodomonas lens and Oxyrrhis marina individually or in combination. Oxyrrhis marina itself was fed up to four of the algae species. The lipid class and fatty acid composition of the copepods was determined and compared with each other, the diets and with wild C. finmarchicus , C. glacialis and Pseudocalanus sp. Cultured O. marina , T. furcata and N. lacustris had greater proportions of essential 22:63 or 20:53 acids than in their diets suggesting nutritional enrichment through synthesis or preferential retention. Lower proportions of 18:33 than in their diets fed individually or in combination suggests desaturation and elongation of 18:33. Stable isotope analysis of the heterotroph samples and their dietary sources revealed similar values for 18:33 in each dietary pair and different ones for 22:63 and 20:53 supporting derivation from precursors rather than trophic magnification. Principal components analysis of copepods and their diets showed cultured Calanus spp. to have the most similar fatty acid composition to their diet indicating little modification or sequestration of polyunsaturated fatty acids.
Print ISSN:
0142-7873
Electronic ISSN:
1464-3774
Topics:
Biology
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